Reflecting optical unit



-.Feb.-9, 1943.

A. M.'TAYLOR 'REFLECTING OPTICAL UNIT Filed March 3, 942

AWMIMML AUGUST TAYLOR,

INVENTOR.

L-EY

ATToRNey Patented Feb. 9, 1943 UNE'E'ED STATES FATENT OFFICE- REFLECTING OPTICAL UNIT AugustM. pTaylor, Fort Collins, 0010. Application March 3, 1942, Serial No. 433,116 3 Claims. (01. 85432) This invention relates to improvements in signs of the light reflecting type and more particularly to the construction of the'units of which the sign is composed.

The widespread use of automotive vehicles provided with powerful headlights has made it possible to construct signs that will be clearly visible at night, utilizing for this purpose the light from the vehicles, and many different constructions of units have been invented and patented.

It is the principal object of this invention to produce a light reflecting sign unit of a very simple construction that will have the property of effecting a wide distribution of reflected light from a single light source so that it will be Visible from a large number of positions regardless of the direction of the incident rays.

Another object is to produce a light reflecting unit that can be moulded and which can be readily secured in position on a support.

A further object is to provide a reflector unit that will respond to light rays making an angle approximating ninety degrees with the axis as well as to rays axially incident.

The above and any other objects that may appear as the description proceeds are attained by a construction that will be described and for this purpose reference will be had to the accompanying drawing in which the invention has been illustrated, and in which:

Figure 1 shows a road along the sides of which sign-s and guide posts, provided with reflecting units embodying this invention, are positioned;

Figure 2 is a diametrical section taken on line 2-2, Figure 3, showing the unit to an enlarged scale;

Figure 3 is a horizontal section on line 3-3 of Figure 2;

Figure 4 is a section, similar to that shown in Figure 2, but to a smaller scale, and shows a slightly modified form of construction.

Figure 5 is a section taken on line 55, Figure Figure 6 is a diametrical section through a reflector unit and shows another means for securing it in place; and

Figure 7 is a section taken on line 1-1., Figure 1.

In the drawing reference numeral I0 designates a roadway, ll guide posts positioned along the convex edges of the curved road and I2 designates a conventional sign. In the drawing the guide posts have been shown as channels to the webs of which a number of reflector units [3 are attached in the manner shown in Figure 7.

It will be observed from Figure 1 that the light from automobile headlights approaching from the right will strike the reflector units at a large angle to their axis and that this angle decreases as the light approaches. If the reflector units are operative only with light striking them in an axial direction or at a small angle to the axis, it is necessary to provide a double set of unitson each post in order to cooperate with automobiles traveling in opposite directions, with the present construction one set of units on each post is sufiicient for reasons that will be hereinafter set out.

In Figure 2 a diametrical section of a unit, to an enlarged scale, has been shown and reference will now be had to this figure for the purpose of describing the invention;

The unit is moulded from clear glass, or some suitable transparent plastic, and the unit has been designated by reference numeral 1 3. The units are solids of revolution symmetrical with respect to the axis .r-y. The base is a plane indicated by reference letters VW which is perpendicular to the axis. Each unit has a central axial opening I l of a diameter 2A and terminates in a semi-spherical surface whose center is at C. That portion of the opening between the center 0 and the plane 17-0, of a length a, is cylindrical and terminates in an outwardly flaring, arcuate surface l5 whose center is at CI in plane b--c. The arcuate surface has been shown as having a radius R but the radius of curvature may be larger or smaller as may be found most desirable. Since surface I5 is a surface of revolution, it is generated by the quadrant arc l5 rotating about axis :v-y and the locus of the center Cl is a circle. That part of the base that has been designated by Z, in Figure 2, is a plane annular zone perpendicular to the axis :c-y. The surface of the opening I 4 is covered with a layer of light reflecting material I6 which may be a coating of mercury or a layer of tin foil. The periphery of the base terminates in a flange I! that serves to hold the metal disk I8. A bolt 19 is attached to disk I8 as shown and the edge 25 of the disk is turned upwardly and inwardly to engage the flange ll. Edge 20 is cut at several places so that it will yield to receive the flange ll. The outer surface of the reflector unit is substantially elliptical when seen in section, as in Figure 2, and the units will be referred to as ellipsoids. Specifically the outer surface is divided into three separate zones, one of which is the polar zone 2|, whose surface is spherical,

its center being at C. In the embodiment illustrated the polar surface has a radius of 2B. Zone 22 is generated by the rotation of an arc whose center is positioned in plane 12-0, at its intersection with the cylindrical surface of opening [4, which center has been designated by reference character C2. The radius of the generating arc has been indicated as 4R. That part of the outer surface between planes b-c and u-w is cylindrical.

The resultant solid is a semi-ellipsoid and instead of having the exact shape shown it may be a true ellipsoid.

In order to show the light dispersing properties the paths of several rays of light have been shown. Light striking the reflector in the direction of line 23 emerges in the direction of line 23a. Light striking the polar surface in the direction of line 24 emerges in the direction of line 24a. Rays of light striking the polar surface in the direction of line 25, which passes through center C will return along the same path while light striking the reflector unit in the direction of line 26 will be reflected from the curved zone l and emerge in the direction of line 26a.

The above examples show that light incident on any portion of the reflector unit surface will be refracted and reflected in various ways and the result is that a beam of light striking the unit will be broken up into innumerable rays that each emerge in a different direction. Units of this type will be visible over a large area when subjected to the action of a beam of light from any source.

In Figures 4 and 5 a slightly modified form has been illustrated. This embodiment difiers from that shown in Figures 2 and 3 in this, that the surface of opening I4 is fluted and the semi-' spherical top divided into angularly related facets. The embodiment illustrated in Figures 4 and 5 will naturally produce a more varied'distribution of the light, which may be desirable in some cases.

In Figure 6, the unit [3 has been shown as attached to a support 21 by means of a bolt 28 that extends through an opening in the polar surface. A gasket 29 is positioned between the unit and the support 21 and forms a weatherproof seal.

The surface of the opening in Figures 4 and 5 is silvered or provided with a reflecting coating, the same as explained in connection with Figures 2 and 3.

From the above it will be apparent that the reflector unit is especially well adapted for signs of all kinds including house numbers and that! signs employing such units will be readable over larger areas than signs employing units of less dispersive power.

Having described the invention what is claimed as new is:

1. An optical unit of the reflector type comprising a transparent body of substantially ellipsoidal shape, having a flat base perpendicular to the major axis, the body having an axially concentric opening extending inwardly from the base, the inner end of the opening being substantially semi-spherical and substantially concentric with the polar area of the body, the surface of the opening at its outer end being outwardly flaring on a substantially circular arc whose outer edge is tangent with the base, the opening having a lining of reflecting material.

2. An optical unit in accordance with claim 1 in which the opening is longitudinally fluted whereby a plurality of angularly related reflecting surfaces are formed.

3. An optical unit in accordance with claim 1 in which an upwardly tapering surface is provided around the periphery adjacent the base for effecting attachment with a cap.

AUGUST M. TAYLOR. 

